Ballistics In The Palm of Your Hand

Point. Click. Shoot.

People the world over drift aimlessly through parks and city streets, like packs of fireflies with the soft glow of smartphones in hand, in search of mythical creatures to capture, battle, and evolve. Their obsession has been cleverly stoked via an augmented reality game that knits together graphics, game play, GPS data, and digital maps — all thanks to the incredible technology now available in smartphones. It’s said that the computing power available in the ubiquitous iPhone outclasses the computers used by NASA to put a man on the moon over four decades ago by millions of times over.

Moving to less frivolous pursuits, that same handheld processing power is being harnessed to increase hit probability for professionals, hunters, and competitors. In this article, we take a look at several ballistics apps that run on your smartphone, as well as a couple of standalone devices. The black science of ballistics meets the world of point and click.

External Ballistics

Once you break a shot and the bullet leaves the barrel, its path — or trajectory — is out of your control. And bullets aren’t like laser beams; you can’t simply point at the target and watch it go straight forth as far as the eye can see. They’re pushed out of your barrel once the powder ignites and fly through the air in an arcing path, like a baseball thrown to home base from the outfield. What happens to your bullet once it’s airborne is referred to as external ballistics.

Generally speaking, the biggest considerations as your projectile flies through the air are gravity, friction, and wind. From a practical perspective, let’s take a look at the variables you’ll typically be concerned with and how they can be measured in the field.

> Range to target: This may be implicit in this discussion, but the distance between you and your intended target is the first key variable, and people are notoriously poor at estimating distance without practice. You might determine it by using a rangefinder, by referencing against known distances, or by estimating using a reticle. It’s also not as simple as you might think when shooting at an angle (see “What’s Your Angle” to understand why). The laser rangefinders in this guide also measure angle of inclination, though not all rangefinders do. Most apps allow you to use your smartphone to estimate angle of inclination as well. One of the apps overlays your position on a map, allowing you to use visual references and landmarks around you to help get a picture of distance to potential engagements.

> Environmental factors: Temperature, air pressure, altitude, and humidity all affect air density, and thus the amount of air resistance that a bullet experiences in flight. You can collect this data directly utilizing handheld weather meters, and you can also use data from nearby weather stations by accessing them over the Internet, putting you at the mercy of your access to a cell signal.

> Wind: This is one of the trickier factors since wind can change substantially along the path of the bullet. So while you can easily measure wind at your own location, you need to be able to assess and account for downrange wind.

> Spin and Coriolis drift: These are more of a consideration at long ranges. Barrels are rifled to impart spin on bullets in order to stabilize them in flight. But bullet rotation causes some sideways movement as it travels downrange, known as spin drift. Some key determinants include bullet length, environmental conditions, and how far along the trajectory the bullet has traveled. Additionally, while the bullet is in flight, the Earth continues to rotate and its movement in relation to the bullet can be noticeable at long ranges — this is called Coriolis drift.

Finally, information about your particular weapon and load are critical, in particular its muzzle velocity and the ballistic coefficient (BC) of the bullet, which is a representation of how well or how poorly it retains velocity as it flies through the air.

Predictive Models

Given knowledge of these variables, a projectile’s trajectory can be predicted reasonably well by a ballistic solver. Once you have a computed trajectory, you’ll know where the bullet should impact at a particular distance as compared to your zero, allowing you to make the necessary adjustments (e.g. holding over or dialing corrections on your scope turrets).

Ballistics solvers use various types of algorithms to model how a projectile behaves in flight. In particular, various drag models predict the all-important air resistance that we mentioned before. They require good information about the particular bullet you’re using to drive their calculations — the most commonly seen BC standards are referred to as G1 and G7. But even those don’t necessarily always exactly match your particular bullet; various apps allow you to input empirical data to true up your observed results with their calculations. Applied Ballistics has also developed custom drag models by testing a variety of specific bullets, and Desert Tech has also utilized Doppler radar data from empirical testing to tweak its flight curves.

Todd Hodnett of Accuracy 1st (see “Zeroed In”) is known for his admonition that “the bullet doesn’t lie.” The wise marksman doesn’t solely rely on calculations and collects empirical muzzle velocity and DOPE (data on previous engagements) for a given weapon system and specific loads. However, having a ballistics solver on tap, especially when you’ve confirmed or trued it against your actual weapon makes it easy to determine specific firing solutions for your exact situation. When lives are on the line, you have a once-in-a-lifetime shot on a hunt, or you’re in the running for a match win, this can make all the difference.

Finally, Bryan Litz of Applied Ballistics emphasizes the old adage, “garbage in, garbage out.” If you don’t feed good data into your ballistic program, you won’t get good results. For example, the muzzle velocity printed on the side of your ammo box often varies quite a bit from reality. Take the time to understand and carefully configure all the inputs in whichever app or system you decide to use.

Fundamentally, the options in this guide are pretty similar, so think about which fits your intended use and which user interface is most intuitive to you. Take a look at which ballistic solver they utilize, plug in some of your own log data, and see how closely the calculated firing solutions match up with your actual results (for instance, Applied Ballistics and JBM Ballistics both have online tools where you can plug in your variables to test drive their calculations, though you can’t access AB’s custom drag curves). There also may be specific unique features that one has, such as custom wind configuration, compensating for cant, logging features, or map integration. And taking the time to calibrate your solver to your particular weapon will really serve you well. But in our testing, even out of the box, all of these apps churned out firing solutions that were within a couple tenths of a mil to our sample gun’s logged DOPE out to 1,500 yards (see sidebar). We probably all have an index card taped to the side of our buttstocks, but for anything more complex any of these ballistic programs offer so much more. It’s hard to go wrong here.

Apps

For our testing purposes, we evaluated iOS versions of popular premium ballistics apps. All of them allow you to:

> Set up profiles for your rifle and ammunition > Obtain firing solutions and generate range cards > Correct for wind and angle of inclination > Compensate for differences between the environmental conditions when you zeroed your weapon and current conditions > Account for spin and Coriolis drift > Download environmental data over the internet from nearby weather stations > Mix and match units (e.g. MOA and mRAD)

The Straight Dope

To get a sense of how closely the calculated drops from all these fancy ballistic programs matched up with actual recorded dope, we compared previously recorded empirical data from a 6.5 PRS rifle with their firing solutions. Please note the following caveats: First, this was a sample size of one, so it’s hardly scientific. Second, there’s plenty of margin for error in the logged DOPE and measurements, not mention that the human factor is involved (note some common variances noted below that we saw in the 500- to 700-yard range). Additionally, since we were working with log data, the Bushnell standalone doesn’t have the ability to analyze “what-if” scenarios, only display real-time results, so we couldn’t include it in this analysis. Its pre-defined curves would have been at a disadvantage anyway; you could instead use it with the bundled Kestrel’s ballistic solver for more accurate results. For more details on the Ruger Precision Rifle, please see “Going Hot.”

Compared to our empirical data from 300 to 1,500 yards, we found the following:

> AB Analytics, Sig Kilo 2400, and Kestrel 5700 Elite: These are all running the Applied Ballistics solver (including AB’s custom drag curves) and generated the same solutions. Out to 1,000 yards, the firing solutions were mostly within 0.1 mil, with the 700-yard solution being off by 0.2 mil and the 400-yard spot on. Out to 1,500 yards, the calculation was off by about 0.2 mil.

> Bullet Flight and Shooter: These two apps are also running Applied Ballistics solvers (sans custom drag curves). Their calculations were identical to each other, but slightly different from the ones above. The solutions generated by these apps were dead nuts on out to 1,500 yards, with no deviation from observed drops except for 0.2- to 0.3-mil variances at 500 to 700 yards.

> Ballistic AE and BallisticsARC: These apps both run the JBM Ballistics solver, and had almost identical solutions. Within 1,000 yards, their predictions were spot on, except again for 0.2- to 0.3-mil deviations at 500 to 700 (sensing a pattern there …). Beyond that, they were off by about 0.1 to 0.2 mil.

> Strelok Pro: Strelok utilizes a proprietary solver. Its results diverged by roughly 0.1 mil out to 1,200 yards, with data points at 900 and 1,000 yards matching up. Beyond that the variances increased up to 0.3 mil at 1,500 yards.

> Trasol: Trasol also has a proprietary solver. Its solutions matched up through 400 yards, then diverged by 0.1 to 0.2 mils out to 1,000 yards. There was one 0.3 mil outlier at 700 yards. Past 1,000 yards, Trasol’s solutions were within 0.1 mil of our DOPE.

App: Peak Studios Ballistic Advanced EditionSolver: JBM BallisticsDrag Models: G1, G2, G5, G6, G7, G8Bullet Library: Yes, plus cartridge libraryMoving Target / Cant: Yes / YesAngle of Inclination / Azimuth: Lay phone flat / Point phoneTruing: Muzzle velocityMSRP: $20URL:www.ballisticapp.comNotes: Ballistic AE is chock full of features. It can configure custom wind settings, with designated speed and direction at different zones along the flight path. It generates graphical charts of trajectory, wind drift, altitude, and angle, as well as a 3D image of trajectory. There’s a HUD feature to tweak inputs and see firing solutions. A range finder function graphically replicates what you see through your reticle in order to calculate the size of a target. You can even upload your own reticle image to use, though you need to know all of its subtensions.

You can save firing solutions as favorites to quickly recall them, and define ballistic profiles that encapsulate info for both your rifle and ammo. We found it a bit fussy to manage multiple ammo with the same rifle, or to go back to modify existing profiles.

Notably, Ballistic AE includes many logging features that are quite nice. You can log range notes, reloading data, record target data, calculate group size, and so on. You can either take a picture of your target or manipulate a graphic representation.

There’s an iPad version that takes advantage of the additional screen real estate, but it’s a separate app for purchase at $20. The iCloud sync feature will synchronize settings across similar devices (i.e. iPhone to iPhone, or iPad to iPad, but not iPhone to iPad).

The mapping feature provides you with a bird’s-eye view of your location. You can set your shooting position and zoom in or out to define multiple targets, and it’ll return distance and firing solutions. If you’re not familiar with the area, it can be a little challenging to translate the overhead view to what you see in front of you. We can definitely appreciate applications for things like setting up blinds and feeders, preparing for a stage at a PRS match, mapping out potential threats and engagements, and so on. An upcoming app update will allow for caching map data before you go off the grid and lose signal. For the time being, we found scrolling around the desired area while you still have signal stores the map data in memory for as long as you keep the app open.

Note that equipment profiles are saved with the rifle and load as a single record entry, so you have to replicate your rifle info if you use multiple loads with it. Also, you can’t generate corrections for movers or canting your rifle. It also doesn’t translate measurements into clicks on your turrets, unlike other offerings here.

App: Bullet FlightSolver: Applied BallisticsDrag Models: G1, G7, G8Bullet Library: Yes, plus cartridge libraryMoving Target / Cant: No / NoAngle of Inclination / Azimuth: Lay phone flat / Manually enterTruing: Calculate BC from muzzle velocity and dropMSRP: $30URL:www.knightarmco.comNotes: The elder statesman of the group, Bullet Flight’s been around since 2009. And it works well, but it feels like it was designed in 2009. The most important settings are close at hand, but we found the user interface not as intuitive as others. Some features are kind of buried — for instance, you can create a new profile for rifle and ammo settings, but to choose from the bullet library, you need to back out to the home screen, tap “Utils” then tap “Projectile Database.” However, once that’s done, you can configure settings and get firing solutions with minimal fuss.

It provides a range card in chart format plus a HUD type of display with wheels to change range and wind. It also has a range estimator where you can type in what you see in your reticle. Other apps can automatically populate latitude and measure azimuth by pointing your phone; you need to manually enter these values into Bullet Flight. Bottom line, it ain’t pretty, but it just works.

App: ShooterSolver: Applied BallisticsDrag Models: G1, G7Bullet Library: YesMoving Target / Cant: Yes / NoAngle of Inclination / Azimuth: Lay phone flat (with timer) / Point phoneTruing: Muzzle velocityMSRP: $10URL:www.shooterapp.netNotes: We liked Shooter’s method of separately configuring firearm and ammo profiles, making it easy and intuitive to set up for multiple loads in the same weapon. Attributes that are relevant to a rifle (such as twist, sight height, Mil vs MOA, etc) are defined in the rifle’s profile, and those relevant to ammo (such as bullet diameter, weight, length, BC, etc.) are defined in the ammo’s profile.

The app then generates a range card in table format, a graph, and a HUD type of presentation of the firing solution, where you can tweak distance, wind, and wind angle. It handles movers, but not cant. Hidden in the settings is a range estimator, where you can type in data on what you see through your reticle to calculate distance.

Shooter is a universal app, working on both iPhone and iPad. The iPad version takes advantage of the expanded screen real estate to present the firing solutions and range card.

App: Strelok ProSolver: ProprietaryDrag Models: G1, G7, plus othersBullet Library: Yes, plus cartridge libraryMoving Target / Cant: Yes / NoAngle of Inclination / Azimuth: Aim with camera or lay phone flatTruing: Muzzle velocity, BCMSRP: $12URL:www.borisov.mobi/strelokproNotes: Many folks might know of Strelok through the free version of this ballistic app. Developer Igor Borisov has packed Strelok Pro full of features, and is known for being very responsive. Strong like ox, it is … and just as attractive. While not the prettiest app in the bunch, everything is close at hand once you figure out what all the icons mean.

You can configure profiles for rifles, ammo, and scopes. Strelok Pro presents the firing solution, a range card table, and a graphical representation of your reticle and target. This last bit is Strelok’s key differentiator. The app features a large library of scopes and reticles, along with subtension data allowing it to display exactly what you should see through your optic. You can plug in your desired distance, the target shape and size, and the app will overlay the calculated hold and target on your reticle — it’s a great feature for 3-gunners in particular.

There are yet more features. You can also build out a target list to tabulate holds for multiple targets at different ranges. It has a point blank range and effective range calculator, an MOA/MRAD converter, and connects to Kestrels and WeatherFlow weather meters to gather atmospheric data. It doesn’t, however, compensate for cant. Whereas most other apps have you lay the phone flat (e.g. on top of the barrel or a rail) to measure angle of inclination, with Strelok you can also aim at your target with your phone’s camera. Strelok Pro is a universal app; on an iPad, it makes use of the added real estate by rearranging the user interface.

App: TrasolSolver: ProprietaryDrag Models: G1, G7Bullet Library: NoMoving Target / Cant: Yes / YesAngle of Inclination / Azimuth: Lay phone flat / Point phoneTruing: NoMSRP: $10URL:www.deserttech.comNotes: DesertTech has made some waves by bringing another ballistic solver to the game, using Doppler radar data from empirical testing to tweak its flight curves and working with Sniper’s Hide to ensure they delivered the features that precision shooters desire.

The user interface is simple, with all settings and configurations jam packed into three screens for you to squint at. Every variable that you would want to tweak is available, though there’s no bullet library, so you have to set up data for all your loads. The company says that bullet libraries will be forthcoming in future updates. Like most of the other apps, gun profiles that you can save and load include configurations for both rifle and ammo, so if you use multiple loads with the same rifle you need to re-enter the rifle’s data.

Trasol displays a range card table as well as a trick HUD display, which shows the view through your phone’s camera while overlaying key data and a firing solution. It also picks up slope, azimuth, and cant based on where you’re aiming the camera.

Additionally, Trasol allows you to set up three downrange wind zones and features adjustments for cold bore variations and zero shifts (e.g. from attaching a suppressor or if your zero is just slightly off between clicks). It, however, doesn’t have a truing function — Desert Tech is very confident in its solver and suggests making small changes to the drag coefficient or zero adjustment if an end user wants to tweak the calculations. The app works on both iPhone and iPad, though the iPad version is just a larger version of the same interface.

App: AB AnalyticsSolver: Applied BallisticsDrag Models: G1, G7, AB custom drag curvesBullet Library: YesMoving Target / Cant: Yes / NoAngle of Inclination / Azimuth: Manual entry / manual entryTruing: Muzzle velocity, drop scale factorMSRP: $200URL:appliedballisticsllc.comNotes: For those who roll old-school, AB Analytics from the wizards at Applied Ballistics is a Windows-based application that encapsulates the latest in AB’s formulas and custom drag curves. It’s a self-contained executable, so their many military customers who aren’t allowed to modify their laptops don’t need to actually install an application on their computer. It can also run on a Mac after jumping through some hoops. Products running AB’s full ballistic package, like the Sig KILO2400ABS and Kestrel 5700 Elite, generated results that matched up exactly with AB Analytics.

AB Analytics generates range cards and specific firing solutions. It also allows for up to 10 wind regions. Notably, it also presents a breakdown of the firing solution, separating gravity drop, coriolis drop, and aerodynamic jump for elevation, and wind drift, coriolis drift, and spin drift for windage. Long-range nerds could spend all day playing with variables to see how they affect the firing solution. The application also has other tools to analyze wind effect, vertical and horizontal uncertainty, hit probability, and shot simulations.

The built-in ballistic program doesn’t offer a full-fledged ballistic solver; rather it has eight pre-defined curves against which you map your particular load and some custom curves that you build by entering drop data. During a range test out to 500 yards, the Bushnell’s firing solution put us on steel, but we wouldn’t feel as confident using pre-defined curves for more precise work at longer distances. It also doesn’t provide wind holds. However, if you have a Kestrel with Bluetooth, like the Sportsman model in this bundle, the Bushnell will use the Kestrel’s ballistic solver to generate precise calculations and display the holdover through the monocular. The distance is relayed to the Kestrel, where you can view other data. They make a nice pair, like Penn and Teller. Note that the Kestrel Sportsman model lacks some features of the Elite shown to the right, including custom drag models, calibration, range cards, multiple targets, and expanded configuration options.

There’s not too much to the smartphone app — you can use it to configure the rangefinder and view distance, angle, and holdover. Street prices are closer to $700 for the rangefinder alone and $1,150 for the Kestrel bundle, which comes with the rangefinder and case, Kestrel Sportsman and case, a tripod-mountable rotating vane, and lanyards.

The ballistics package is based on Applied Ballistics’ solver, with its full functionality, bullet library, and custom drag models. While the screen is clear and easy to read, with a handy backlight, it’s also fairly small. So the user interface to access all the ballistics features is somewhat cramped. But once you get the hang of it, you can choose between 16 rifle and ammo profiles, view firing solutions and a range card, pull in environmental conditions, tweak settings, and create multiple target configurations.

With the optional Bluetooth connectivity, you can utilize Kestrel’s smartphone app to more easily configure settings and set up custom drag models for your loads. It also provides a HUD display of your firing solution and a handy look at holds for multiple targets. Unfortunately, you can’t view your range card except on the Kestrel’s small screen — only four entries at a time. There’s a lot more that Kestrel could do with its app. Still, the only thing really missing from this system is a rangefinder, angle inclination, and GPS; products like Bushnell’s Elite ARC slot right in, and you can pull GPS data off your smartphone. In addition, other apps like Ballistic AE and Strelok Pro can connect to LiNK-enabled Kestrels to pull atmospheric data.

To top it off, SIG built the Applied Ballistics solver into the unit, quickly generating firing solutions in the standalone device and showing it in the display. The only missing input is wind — you can manually enter your own wind calls, or utilize the provided WeatherFlow wind meter via your smartphone.

Speaking of smartphones, Bluetooth allows you to connect to the KILO2400 using SIG’s app, which is intended more to configure settings than to act as a user interface for the rangefinder. Still, it provides a HUD display, and you can use it as a remote, if for instance you have the rangefinder mounted on a tripod. You can create and load four different rifle/ammo profiles onto the KILO (including AB’s custom drag models), but you’ll have to remember which is which since you can’t give them names that display on the unit.

We were quite impressed with the compact KILO, though we couldn’t fully wring out the system as a bug in the app caused it to crash whenever we ranged something. Another complaint: The rangefinder has brightness settings; it starts in auto mode, but we inadvertently clicked on it and the first thing it did was cycle down to its lowest mode. Naturally, low mode is not at all visible during the day, and we thought we broke it. Now you know. The KILO2400ABS comes with a case, MOLLE gear bag, wind meter, tripod adapter, lanyard, and extra batteries.

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